2003 Ford Ex 4X4 V10 6.8L XLT

First, there's a slight rattle noise coming from underneath the truck. I can't pinpoint from where exactly, I haven't crawled under it while it's running but can hear it mostly while I'm standing on the side, near the middle of the truck. From the front, I can't hear it, and I can barely hear it while I'm in the engine compartment with the hood up, from the front it sounds like it's coming from under the truck area. It's almost like a slight tapping/rattle noise. I have a fear of rods knocking, but aren't those more prominent? I can't hear if it's RPM related because once I rev the engine even slightly, the engine noise becomes louder than the rattle, it's that faint. I tried getting some video that had the sound in it, but my camera wouldn't pic that sound up over the engine. When I tap the heat shield coming from driver side headers it rattles, passenger side does not, possible culprit? Cat is brand new, no rattle there, muffler is about 1000 years old, who knows.

Secondly, while underneath the truck "hanging out" as I told my wife, I found a hose coming from the front pumpkin, that leads to nowhere. It's a rubber hose, that is clipped on to the frame. There aren't any other hoses around there that it could connect to, so is there some sort of drain running from the front axle? It's connected to the top of the pumpkin, I'll take a pic whenever I get some sleep and am more awake this evening. Just curious if this is something that needs to go somewhere or be plugged off...it almost looks like a vacuum line but why on earth would it come from there? Edit:: Is it the axle drain tube? If so, what's that thingamabob for?

 

I can’t help with the rattle, but the hose coming off the top of the pumpkin is the breather tube for your differential, there should be one on the rear diff. as well. It allows to diffs. to breath, but keeps water and debris from getting in them, unless you go through water that is deeper then the top of the tube. Then you get to replace the fluid in the diffs.

 

Haha, awesome thanks so much. And Welcome to FTE!

 

Check the sheet metal covers near the transmission and torque converter. They are known to loosten and rattle on the EX. Search the forum for more on how to diagnose that and fix it.

If you are concerned about a tapping in the motor, get out a large screw driver and use it like a mechanics stethiscope, metal end on motor, plastic end on ear with the motor at idle. If you don't hear it in there after checking all four corners of the motor, it's probably not internal.

 

What part of the motor would I put the stethoscope on? It doesn't sound like it's coming from the engine compartment, almost sounds more from the axle area, however it sounds like it's tapping with the rhythm of the engine.

 

The tapping doesn't appear to be RPM sensitive. It stays the same no matter what RPM I'm at, doesn't increase under load at all. It almost sounds as if it's coming from the axle somewhere, hell I don't know. This has got me a bit worried about throwing a dang rod in this thing. It's always been there, I guess the exhaust leak covered it up though.

 

Also, I recently changed the oil and used 5w-20, would it be adviseable to try changing the oil for say, 5w-30 and see if that coats and quiets?